Fish and other wildlife that have been nearly decimated by acid-rain damage to lakes can quickly recover if acid-forming industrial pollution is reduced, researchers reported Wednesday.
Although many studies have shown acid levels of streams and lakes may return to nearly normal if harmful pollution is cut, evidence has been lacking about whether marine life living in acid-stressed waters can also bounce back after emission reductions.Now, two Canadian researchers have found that some populations of acid-sensitive fish, leeches, crayfish, worms and microscopic animals may stage a "rapid recovery" once pollution is reduced and lakes and streams become less acid.
In a study published in the British journal Nature, J.M. Gunn of Laurentian University in Sudbury, Ontario, and W. Keller of Ontario's Ministry of the Environment looked at the impact of reducing industrial emissions of sulfur on the marine life of Whitepine Lake.
At the start of the study, "The lake was acidic and its fish population showed classical signs of acid stress: Acid-tolerant yellow perch were very abundant, while acid-sensitive species such as lake trout and white suckers were extremely rare and were not reproducing," the researchers wrote.
From 1980 through 1988, with sulfur emissions less than one-half 1974 levels, the acidity of the lake gradually dropped and water quality improved significantly.
"The first evidence of biological recovery was the appearnce of naturally produced lake trout from the remnant adult population. Young lake trout first appeared in 1982 and became increasingly abundant throughout the rest of the study," Gunn and Keller said.
Also staging a comeback were Iowa darters, a type of bottom-dwelling fish, leeches, crayfish, mayflies and bottom-dwelling worms.